1. Field of the Invention
This invention relates to a process for encapsulating metallocenes by the in situ polymerization of urea and formaldehyde to form the capsule shell wells.
2. Prior Art
Microencapsulation of materials, whether solid, liquid or gas, is very well known in the art. More specifically, encapsulation of materials in durable shells of urea-formaldehyde has been described in U.S. Pat. No. 3,516,941 to Matson and, in a related case, British Pat. No. 989,264 in the name of Minnesota Mining & Mfg. Co. Insofar as relevant to the present invention, the disclosures of both those references are incorporated herein by reference. Microcapsule shell walls prepared by copolymerization of urea and formaldehyde are desirable for many applications because of their normally excellent toughness, i.e., resistance to premature breakage, and ability to resist leakage of the capsule contents. While the patents named above do provide instructions for the preparation of urea-formaldehyde shells, these instructions are not fully suitable for all materials. In particular, the procedures of those patents are not adequate for the encapsulation of that class of organic chemical compounds known as metallocenes.